Shear strengthening of RC deep beams with opening using SHCC applied in varying strengthening configurations

The current study aims to evaluate the potential of Strain Hardening Cementitious Composites (SHCC) for shear strengthening of Reinforced Concrete (RC) deep beams with openings. The test matrix included fifteen deep beams with square web openings. All beams had identical dimensions of 1700 mm in length, 500 mm in depth, 500 mm in shear span, and 150 mm in width. The beams were divided into five groups, each containing three deep beams with opening sizes of 150 × 150 mm, 200 × 200 mm, and 250 × 250 mm. One group of beams was tested without any strengthening, while the remaining groups were strengthened with a near-surface-embedded (NSE) SHCC jacket of 25 mm thickness, using three different configurations. Groups II and III were strengthened along the entire shear span with unreinforced and steel-reinforced SHCC (R-SHCC) jackets, respectively. To reduce costs, group IV received R-SHCC strengthening only on the upper and lower chords of the openings. Finally, in group V, R-SHCC strengthening was applied to the shear spans before and after the openings. The test results showed a significant increase in shear capacity, reaching about 80 % when using R-SHCC jacket along the full shear span. Partial strengthening on just the upper and lower chords achieved nearly the same results as full shear span strengthening for beams with 150 mm openings. However, as the opening size increased, the improvement in shear capacity decreased. Strengthening before and after the opening did not improve the shear capacity or ductility. An analytical model based on the strut and tie method (STM) was proposed and evaluated for the shear capacity of RC deep beams with openings. The predicted results closely matched the experimental data. • Fifteen RC deep beams divided into five groups, each containing three beams with three different opening sizes, were prepared. • Four groups were strengthened using SHCC employing different strengthening configurations. • The strengthening configurations were strengthening the whole shear span, strengthening the upper and lower chords only, and strengthening the shear span before and after the opening. • The test results revealed a considerable enhancement in the shear capacity, reaching about 80 % with the use of a steel-reinforced SHCC jacket at the full shear span. • Based on the strut and Tie method (STM), an analytical model for the shear capacity of RC deep beams with openings was proposed and evaluated.